CLINICAL CHEMISTRY WATER BALANCE & ELECTROLYTES Part Two 1

E LECTROLYTES Electrolytes 2

E LECTROLYTES General dietary requirements Most need to be consumed only in small amounts as utilized 3

E LECTROLYTE F UNCTIONS 4

E LECTROLYTE P ANEL Panel consists of : 5

A NALYTES OF THE E LECTROLYTE P ANEL Sodium (Na)– 6

F UNCTION : S ODIUM Influence on regulation of body water Neuromuscular excitability Na-K ATP-ase Pump 7

R EGULATION OF S ODIUM Concentration depends on: Renal regulation of sodium Kidneys can conserve or excrete Na+ depending on ECF and blood volume 8

R EFERENCE R ANGES : S ODIUM Serum Urine (24 hour collection) 9

S ODIUM Urine testing & calculation: 10

D ISORDERS OF S ODIUM H OMEOSTASIS Hyponatremia: < 136 mmol/L Causes of: Hypernatremia:> 150 mmol/L Causes of: 11

H YPONATREMIA 1. Increased Na + loss 12

H YPONATREMIA 2. Increased water retention 13

H YPONATREMIA 3. Water imbalance 14

S ODIUM Note: 15

C LINICAL S YMPTOMS OF H YPONATREMIA Depends on the serum level 16

H YPERNATREMIA 1. Excess water loss 17

H YPERNATREMIA 2. Increased intake/retention 3. Decreased water intake 18

C LINICAL S YMPTOMS OF H YPERNATREMIA Involve the CNS 19

S PECIMEN C OLLECTION : S ODIUM 20

A NALYTES OF THE E LECTROLYTE P ANEL Potassium (K + ) the major cation of intracellular fluid Diet easily consumed by food products such as bananas 21

F UNCTION : P OTASSIUM Critically important to the functions of neuromuscular cells 22

R EGULATION OF P OTASSIUM Kidneys Diet Cell Uptake/Exchange 23

R EFERENCE R ANGES : P OTASSIUM Serum (adults) Newborns Urine (24 hour collection) 24

D ISORDERS OF P OTASSIUM H OMEOSTASIS Hypokalemia Hyperkalemia 25

H YPOKALEMIA 1. Non-renal loss 26

H YPOKALEMIA 2. Renal Loss 3. Cellular Shift 4. Decreased intake 27

M ECHANISM OF HYPOKALEMIA 28 K + moves into RBCs to preserve electrical balance, causing plasma potassium to decrease. ( Sodium also shows a slight decrease ) RBC

C LINICAL S YMPTOMS OF H YPOKALEMIA 29

H YPERKALEMIA 1. Decreased renal excretion 2. Cellular Shift 30

H YPERKALEMIA 3. Increased intake 4. Artifactual 31

C LINICAL S YMPTOMS OF H YPERKALEMIA 32

S PECIMEN C OLLECTION : P OTASSIUM 33

A NALYTES OF THE E LECTROLYTE P ANEL Chloride (Cl - ) 34

F UNCTION : C HLORIDE 35

R EGULATION OF C HLORIDE Regulation via diet and kidneys 36

R EFERENCE R ANGES : C HLORIDE Serum 24 hour urine CSF 37

D ETERMINATION : C HLORIDE Specimen type

D ISORDERS OF C HLORIDE H OMEOSTASIS Hypochloremia Hyperchloremia 39

H YPOCHLOREMIA Decreased serum Cl 40

H YPERCHLOREMIA Increased serum Cl 41

A NALYTES OF THE E LECTROLYTE P ANEL Carbon dioxide/bicarbonate (HCO 3 - ) Total plasma CO 2 = HCO H 2 CO CO 2 42

F UNCTION : B ICARBONATE ION ___________________________________________ continuously produced as a result of cell metabolism, the ability of the bicarbonate ion to accept a hydrogen ion makes it an efficient and effective means of buffering body pH dominant buffering system of plasma 43

R EGULATION OF B ICARBONATE ION Acidosis: Alkalosis: 44

R EGULATION OF B ICARBONATE ION Kidney regulation requires the enzyme carbonic anhydrase - which is present in renal tubular cells & RBCs Reaction: 45

R EFERENCE R ANGE : B ICARBONATE ION Total Carbon dioxide (venous) Bicarbonate ion (HCO 3 – ) 46

S PECIMEN C OLLECTION : B ICARBONATE ION 47

E LECTROLYTE BALANCE Anion gap – 48

E LECTROLYTE S UMMARY 49 cations (+) Na 142 K 5 Ca 5 Mg mEq/L anions (-) Cl 105 HCO3- 24 HPO4- 22 SO4-2 1 organic acids 6 proteins mEq/L

A NION G AP Anion Gap Calculation s 50

F UNCTIONS OF THE A NION G AP Causes in normal patients Increased AG – Decreased AG - 51

R EFERENCES Bishop, M., Fody, E., & Schoeff, l. (2010). Clinical Chemistry: Techniques, principles, Correlations. Baltimore: Wolters Kluwer Lippincott Williams & Wilkins. donating-blood-plasma/ m Sunheimer, R., & Graves, L. (2010). Clinical Laboratory Chemistry. Upper Saddle River: Pearson. 52